We are running Xen 4.0 on Debian Squeeze. We have set up a 2-node cluster and successfuly migrate vm instances between them.

But we want to be able to select a particular nic to handle the migration traffic. Xen documentation and discussion sometimes refers to a hypothetical network configuration in which 'one network interface goes to the outside world, and the other, connected by crossover cable, handles xen management, including migration.'

Right, so how is this setup achieved, such that migration travels only over one nic on each of the 2 nodes, the xend xm commands having been bound to travel over that nic?

An example command, assuming box1 and box2 are the 2 nodes:

box1# xm migrate lucidxentest.phon box2 --live

To be clear, I am pretty sure this is not a vm (domU) configuration issue; rather a dom0 configuration issue.

Is the binding to a particular nic achieved through Xend configuration? or is it done externally, by adding routes, etc.?